The invention relates to a single-pole breaking unit comprising a rotary contact bridge, at least one stationary contact operating in conjunction with said contact bridge and connected to a current input conductor, a rotary bar having a transverse hole accommodating said contact bridge with clearance, which contact bridge is salient on each side of the bar, said rotary bar being inserted between two side panels of the breaking unit, said side panels being substantially parallel to one another. The rotary contact bridge also comprises two sealing flanges respectively placed between the radial surfaces of the rotary bar and the side panels to ensure tightness between the inside and the outside of the breaking unit. At least one arc extinguishing chamber opens onto an opening volume of the contact bridge.
The invention also relates to a switchgear device comprising such a breaking unit.
The invention also relates to a circuit breaker comprising such a switchgear device.